Traffic control system



July 13, 1954 g. MCKNIGHT 2,683,868

TRAFFIC CONTROL SYSTEM Filed Nov. 4, 1949 3 Sheets-Sheet 1 11 INVENTOR. L- CHARLES L. McKNIGHT.

' His Hhbrneys.

July 13, 1954 MCKNIGHT 2,683,868

TRAFFIC CONTROL SYSTEM Filed Nov. 4, 1949 3 Sheets-Sheet 2 INVENTOR.

CHARLES LN KNIGHT. gaga BY wyw y 1954 c. M KNIGHT 2,683,868

TRAFFIC CONTROL SYSTEM Filed Nov. v4, 1949 3 Sheets-Sheet 5 TRAFFIC. Lass-n- I400".

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I a lzs mz INVENTOR. CHARLES LflcKNIG'H'E Patented July 13, 1954 UNITED STA'FtZfi EFATENT GFFICE TRAFFIC CONTROL SYSTEM Charles L. McKnight, Dayton, Ohio Application November 4, 1949, Serial No. 125,583

21 Claims. 1

This invention relates to a traffic regulating signal system and more particularly to a system in which means are provided for controlling the speed of the traflic approaching intersections of the type provided with stop and go lights.

Every driver prefers to regulate his speed so as to reach a controlled intersection when the light is green, but unless one is familiar with the timing of the lights, this is a very diiiicult thing to do. Where it is possible to properly regulate the speed so that one does strike the light right, one saves on brakes and eliminates the delay which result from making a stop. Furthermore, the number of cars which can pass an intersec tion on a green light is much smaller when all cars have to come to a stop before starting up than when all cars are in motion as they approach the light. The inconvenience of having to make complete stops is especially great in the case of heavy trucks which require a much greater distance in which to stop and which require a long period of acceleration after each stop.

It is an object of this invention to provide means for indicating t0 the drivers what speed to travel as they approach an intersection having a stop and go light so as to avoid the need for coming to a complete stop and so as to expedite the handling of trafiic.

It is another object of this invention to provide a simple and inexpensive arrangement which may be used in combination with standard traffic light regulating systems.

More particularly, it is an object of this invention to provide a control which may be added to existing raific light control mechanisms.

Another object of this invention is to provide a simple arrangement which makes it possible to conveniently tie in the speed indicating mechanism with the tramc light system and yet mount the speed indicating mechanism at a distance from the intersection.

Another object of this invention is to provide a control in which the speed indicating means may readily be adjusted to compensate for changes in the timing of the stop and go periods, et cetera.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.

in the drawings:

Figure 1 diagrammatically illustrates a conventional highway intersection provided with a series of red and green cue lights arranged at spaced intervals along the approaches to the intersection;

Figure 2 is a view similar to Figure 1 but showing a modified arrangement of cue lights and speed indicating means;

Figure 3 is a schematic circuit diagram showing the circuits used for controlling the cue lights;

Figure a is an elevational view of an adjustable cam arrangement for use in the operation of the cue lights;

Figure 5 is a schematic diagram showing a modified circuit arrangement;

Figure 6 is a fragmentary elevational View showing one form of speed indicating sign;

Figure 7 is a schematic view showing a still further modification of a speed indicating arrangement; and

Figure 8 is a sectional view taken substantially on line 88 of Figure '7.

In Figure 1 of the drawings, I have schematically shown a pair of intersecting highways l0 and [2 provided with a conventional stop and go light unit I4 for use in controlling the flow of trainc at the intersection of the highways. For purposes of simplification of the illustration, I have shown only the one centrally mounted stop and go light unit for directing the traffic on highway 12. This light unit is intended to represent the conventional type of stop and go light units now extensively used. In actual practice separate stop and go light units are usually pro,- vided for each approach to the intersection. For convenience of description, a red light at the intersection will be referred to as a stop light, whereas a green light at the intersection will be referred to as a go light.

A series of cue light units It are provided along one side of each of the approaches to the intersection, as shown, in order to indicate to the drivers not only that there is a tramc light at the intersection but also to give some indication to the drivers approaching the intersection how fast they should drive in order to reach the intersection when the light is green. Each cue light unit in the series includes a red light it and a green light 26. The operation of these lights is synchronized with the operation of the Stop and go lights forming a part of the unit 54, as will be explained more fully hereinafter.

The phase relationship between the cue lights and the stop and go lights is such that if a driver approaches the intersection at a time when he normally can expect to have a green or go light, the cue light opposite him on the driveway will indicate green. The motorist noting the one light to be green continues on at normal speed, but if the cue light opposite him happens to be red, he reduces his speed so as to arrive at the intersection after the trafiic light has switched back to green. By providing a series of cue lights at each approach to the intersection, the motorist is afforded a number of check points along the way from which to gauge his rate of approach. In this system the motorist is obviously allowed some degree of freedom in the selection of the proper approach rate. If the first cue light encountered is green, but the second cue light just turns to red before the driver gets to it, then the driver will know that he will either have to drive faster to make the go light or slow down and wait for the next go light. However, if the first cue light encountered has just turned to green and the driver comes to the second cue light before it turns to green, this will indicate that he is traveling too fast and must slow down lest he get to the intersection too soon for the light there to change to green. The distance between the cue lights and the number of cue lights used may be varied without departing from the spirit of my invention. Six cue lights have been shown along each approach for purposes of illustrating my invention. The first cue light encountered by a driver should preferably be located at least a quarter of a mile away from the intersection, so as to give the motorist time to adjust his speed. All of the distance involved should take into consideration the maximum speed allowed on the highway, the timing of the stop and go periods, the condition of the highway, et cetera.

Referring now to Figure 3 of the drawings wherein I have shown somewhat diagrammatically the circuit arrangement used in controlling the energization of the various lights, reference numerals 30 and 32 designate the main power lines from which power is supplied to a constant speed motor 34 which is used for driving the timing cams 36, 38 and 40 through the gear reduction device 42 and the cam shaft 35. The motor 34 and the timing cams operated thereby are located within a common housing 43. The cam 36 operates a switch 44 which controls the energizaton of the amber light 46 in accordance r with standard practice. The cam 38 operates the double throw cam switch 48 which in turn controls the red and green lights 50 and 52 respectively. Since the construction and operation of the mechanism for controlling the operation of the red, green and amber lights at the intersection is of standard construction, no further description of this apparatus is is considered necessary.

The cam 40, which is mounted on the same shaft as cams 36 and 38 and which consequently rotates in synchronism with the cams 3'6 and 38, is used for controlling a series of double throw cam switches 54, B, 58, 60, 62 and 64 which control the operation of the red and green cue light units 66, 68, 10, 12, 14 and 16 respectively. In order to simplify the description, the cue lights for only two of the approaches to the intersection have been shown in Figure 3. The cue lights for the other two approaches would be connected in parallel with the cue lights shown. It will be noted from the above described arrangement that the arrangement of the cam operated switches with respect to the cam 40 is such that successive cue lights are successively lit along the highway in a predetermined sequence and in a predetermined phase relationship to the stop and go lights at the intersection. After the one light nearest the trafiic signal turns green, the traffic signal also turns green. Thus, traffic which follows the green cue lights will approach the traffic light at the go signal.

At normal intersections the cue lights mounted along one highway will operate in synchronism with the cue lights mounted along the intersecting highway except that when one of the cue lights along the one highway is green, the correspondingly located cue light on the other highway will obviously indicate red.

In order to attract the attention of the motorist to the presence of the cue lights, a special blinker means has been incorporated. This blinker means comprises a gear which is driven from the cam shaft 35. The gear 84 drives a small gear 86 which causes periodic tilting of the mercury switch 38 through the pivoted links 90 and Q2. The link 92 has its one end pivotally supported on a fixed pivot pin 84 so that as the gear 85 rotates, the mercury switch 88 will be tilted in such a manner as to out the resistance element 96 into and out of the circuit leading to the cue lights.

In the circuit diagram shown in Figure 3, the arrangement of the switches indicates that the traffic light has just turned red on the highway leading to the right and the first cue light or the one light farthest from the intersection on this same highway has turned green. As the time passes, additional ones of the cue lights will turn green, so that a driver opposite the light 56 seeing that light green and the lights ahead of him red will know that he should not drive too fast or he will overtake the red cue lights and will reach the intersection before the go light comes on. Likewise, if a driver while opposite the cue light 68 observes that the cue light 66 is red and the cue light 68 has just turned red but that the cue light 1!] is still green, he can by traveling fast enough reach the subsequent cue lights before they turn red and can consequently arrive at the intersection when the light is still green.

In Figure 2 of the drawings, I have shown an arrangement somewhat similar to the arrangement in Figure 1, but in place of providing a large number of individual pairs of red and green one lights without any speed rates indicated thereon, this figure shows an arrangement in which the same number of pairs of cue lights are provided but in which the pairs of cue lights are grouped together in groups of three and mounted in a housing 69 mounted on a post H beside the highway, as shown in greater detail in Figure 6. Adjacent each set of one lights there is provided a number which designates the recommended rate of speed to travel for reaching the intersection when the light is green. The mechanism for operating these cue lights would be similar to the mechanism used for operating the cue lights shown in Figure 1 of the drawings. The timing for these cue lights can be varied by varying the setting of the cam operated switches as explained hereinafter.

In Figure 4 of the drawings, I have shown in greater detail an illustrative arrangement which makes it possible to adjust the position of the cam followers of a particular cam operated switch mechanism, so as to adjust the individual timing of the switches to meet traffic conditions. As shown herein, the switches 64, 62 and 60 may be adjustably mounted on a fixed supporting plate 9! which is provided with a series of slots 93 as shown. The position of each switch on the plate may be adjusted by loosening the screw 95 which holds the switch in adjustment.

Again referring to Figure 5 of the drawings wherein I have shown in detail single speed indicating sign $9 for use in a system in which several cue lights are mounted together in a single housing, as shown in Figures 2 and 6, and in which numbers indicating the recommended speed have been placed adjacent each set of cue lights, it will be observed that the arrangement is such that if one approaches the intersection at one given time, the green lights opposite the numbers 39 and 45 and the red light opposite 20, may, for example, be energized, thereby indicating that one should travel between 30 and 45 miles per hour in order to reach the intersection when the light is green. The switches 55, 5! and 53, which are used for controlling these lights, are operatel by the cam its which corresponds to the cam it shown in Figure 3. Additional cam-s would be used for each set of speed indicating signs 69, but in order to simplify this disclosure, only the one set has been shown, as anyone skilled in the art could easily add additional sets.

All of the primary controller cams are driven from the same cam shaft and are thus synchronized with the traffic light arranged at the intersection. The speeds indicated opposite the green lights are the correct speeds to be used, whereas the speeds opposite the red lights indicate the speeds which should not be used if one wishes to reach the intersection when the light is green. Under certain conditions one may, for example, have a choice between speeds of 20 or 4-5 miles per hour or some such similar choice.

Figure 6 of the drawings shows a preferred arrangement of the lights and nomenclature to be used in each indicator unit. However, it is to be understood that other arrangements could be used insofar as certain aspects of applicants invention are concerned. The speeds indicated are used for purposes of illustration only.

In Figure '7 of the drawings, there is shown a refinement of the speed controller sign which provides continuously changing approach speed rate information. In this modification reference numeral let! designates a conventional constant speed timing motor which operates the traffic light control cams NH and H32 through a gear reduction mechanism 195. The cams it! and H22. operate the traffic light control switches H95 and I65 which correspond to the switches i l and d5 shown in Figure 3 of the drawings. The cam on is mounted directly on the main shaft 1'88 which also drives a selsyn transmitter Hi). The selsyn transmitter lid is electrically connected to a complementary selsyn motor H2 which may be located at a distance from the intersection and which will serve to operate the drive shaft li t in synchronism with operation of the drive shaft let. The transmitter lit and motor H2 are energized from the main power lines H3 and H5 as shown. Selsyn systems of this type are well-known in the art and need no further description.

The shaft M l is provided with a pulley H6 which in turn drives an endless belt 158. .An idling pulley I29 helps to support the endless belt opposite the window 522 in the indicator housing I23. The belt H3 is provided with suit able speed indicia which serve to indicate to the motorist driving along the highway the perno speed indicia.

missible range of speed which should be adhered to in order to approach the intersection when the light is green. The arrangement is such that a motorist may travel at any of the speeds given on that portion of the belt which is visible through the window at any one time.

It is recognized that trafiic approaching a controlled intersection should not travel at excessive speeds and it is likewise recognized that it is not practical to have the traffic approach the intersection at the slowest possible speed and consequently it is desirable to so construct and arrange the speed indicators so as to avoid these objectionable extremes in speed, even though these extremes would allow the motorist to reach the intersection when the light is green. Consequently, it is preferable to design the speed indicators in a manner that only the more practical speeds are recommended.

The arrangement in Figure 7 illustrates one way in which it is possible to avoid using such objectionable speeds. In referring to Figure 7, it will be observed that a short length of the end.- less belt has been blanked out. Inasmuch as the light remains green for an appreciable time, it is obvous that a driver approaching the intersection will be allowed a certain amount of latitude in his speed and yet strike a green light. It is also obvious that there will be times when he will be required to either travel at a high rate of speed, such as 45 or 50 miles an hour, in order to reach the intersection when the light is green or to travel at a much lower speed, such as 1-5 or 20 miles an hour, so as to allow time for the light to change from green to red and back. to green. Since it is desirable to keep the trafiic moving at a rate of speed at all times and to have a maximum number of cars pass the intersection on each green light, it is not practical to suggest to a driver that he should drive only 15 miles an hour while approaching the intersection even though by so doing he would still reach the intersection just before the light turns red. Motorists who drive slower than necessary when approaching the intersection hold up others behind them who want to make the same light but who cannot make the light if they have to stay behind a driver traveling at a speed just fast enough to reach the intersection the instant before the light changes to red. Consequently the endless belt is provided with a blank zone l26 which contains This blank zone represents a speed which would either be in excess of the safe speed limit or would be too slow for eificient handling of the traffic. That portion of the belt which is not visible through the window 422 of Figure 7 has speed values between 20 and 4-5 given thereon. The exact speed values used may be varied. For purposes of illustration, I have chosen to indicate speed in equal increments of 5, so that the numbers on the hidden part of the belt are 25, 30, 35 and 40. Since the distance traveled in a given period of time varies with difierent speeds, it is obvious that the spacing of the numbers on the belt would not be uniform if the speed increments used are equal.

In order to avoid needless complications and needless repetition in describing the construction and operation of the modification shown in Figures 7 and 8, only the one speed indicator has been shown, whereas in actual practice additional speed indicators would be provided. Thus, at least one speed indicator would be located adjacent each approach to the intersection. While one such indicator spaced at a distance from the intersection would serve the purpose, two or more such indicators spaced from one another would better indicate to the driver the recommended speed over a longer section of the highway.

slippage between the belt IIB and the drive pulley IIS may be prevented by using any conventional type of positive drive connection between the pulley H6 and the belt H8. For purposes of illustration I have shown the pulley II6 provided with pins I30 for engaging the holes I32 provided in the one edge of the belt as shown.

Certain aspects of my invention are equally applicable to an indicator in which the endless belt is eliminated and a large drum (not shown) is substituted for the pulley H6. The recommended speeds would then be shown directly on the periphery of the drum.

The selsyn transmitter I I and its complementary selsyn motor II2 are conventional self-synchronizing untis which are now well-known in the art and which need no further description. These units I It and I I2 insure operation of the endless belt HS in a predetermined synchronized relationship to the operation of the stop and go lights I4 located at the intersection of the highways. A, speed change gear unit I34 is provided for stepping up the speed of the pulley IIG so that the operation of the belt will be timed properly with the operation of the lights at the intersection.

The operation of each of the speed indicating means described herein and the arrangement of the speed indicia thereon would, of course, be designed so as to be synchronized with the stop and go lights at the intersection in such a manner as to take into consideration the distance from the indicator to the intersection.

lhe system of indicating recommended speeds groups the traflic into platoons, the apparatus for controlling the recommended speeds operating cyclically, so that the minimum speed is indicated to the advance traific of a group or a platoon and the maximum speed is indicated to the trailing traffic of the same group or platoon, thereby punching the traffic as it approaches the intersection.

It is recognized that attempts have previously been made to provide devices designed to inform motorists approaching an intersection what percentage of the stop or go period indicated by the control light has elapsed, but such devices which consider time only and not distance to be traveled do not give the motorist adequate information to accurately determine the speed one should travel over any great distance in order to reach th intersection when the light indicates go. Since not all stop and go lights are timed alike, any indicator which merely indicates to a driver the percentage of the cycle left becomes more or less meaningless. Furthermore, indicators of this type are located at the intersection and give the same kind of indication to all motorists irrespective of their distance from the intersection. By virtue of applicants improved arrangement, the mot rists approaching an intersection is not only given advance notice of the presence of a stop and go light at the intersection but is given explicit instructions as to how fast to drive the distance from the speed indicator to the intersection in order to reach the intersection at the right time to avoid the need for stopping.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. A speed guide for use in indicating the speed to be traveled on a highway while approaching an intersection having stop and go lights comprising a speed indicating means mounted adjacent the highway at the approaches to the intersection to be viewed by persons traveling over the highway, a series of indicia on said indicating means, each designating a particular speed, a timer operating continuously through a complete cycle of operation, first means operated by said timer for controlling the operation of said stop and go lights, and second means operated by said timer for controlling said speed indicating means in synchronism with said stop and go lights.

2, In apparatus for controlling the flow of traffic at the intersection of two or more highways, the combination, stop and go signal means, a speed indicator mount-ed at a station adjacent one of said highways to be viewed by persons traveling over said one highway, a series of indioia on said speed indicator at said station, each indicia designating a particular speed, a timer including a series of timer contacts, and circuit means connecting said stop and go signal means, said connecting means connecting in seriatim said series of the indicia of said speed indicator to said timer contacts whereby said series of speed indicia is operated in synchronism with said stop and go signal means.

3. In a traffic regulating system for use in controlling the fiow of traffic past an. intersection comprising in combination, trafiic control signal means at the intersection, variable speed indicating means for giving a recommended speed 'which is a function of distance and the time available to reach the intersection when the signal at the intersection indicates go, said speed indicating means being spaced from said intersection along the highway approaching the intersection, and means for synchronizing the operation of said speed indicating means with the operation of said control signal means.

4. In a trafiic regulating system for use in controlling the flow of traffic past an intersection comprising in combination, traffic control signal means at the intersection, speed indicating means spaced from said intersection along the highway approaching the intersection, and means for synchronizing the operation of said speed indicating means with the operation of said control signal means, said last named means comprising a first motor for operating said traflic control signal means, a second motor for operating said speed indicating means, and means for synchronizing the operation of said motors, whereby the speed indicated by said indicating means bears a direct relationship to the operation of said trafiic control signal means.

5. In an apparatus for controlling the flow of trafiic at an intersection of two or more highways, stop and go signal means of the type in which traffic is allowed to cross the intersection on only one highway at a time, speed indicating means mounted to be viewed by persons traveling over one of said highways including a plurality of numbered means for cyclically indicating recommended speeds in terms of miles per hour, and means for operating said speed indicating means in synchronism with said stop and go signal means.

6. In an apparatus for controlling the flow of traiiic at an intersection of two or more highways, stop and go trams control lights, a motor, switch means for controlling said lights, and means operated by said motor for periodically opening and closing said switch means, a selsyn transmitter drivingly connected to said motor, a selsyn motor mounted remotely from said transmitter at a point along said one highway, and speed. indicating means operated by said selsyn motor whereby said speed indicating means is synchronized with the operation of said traffic control lights.

'7. In an apparatus for controlling the flow of trafiic at an intersection of two or more highways, stop and go trafiic control lights, a motor, switch means for controlling said lights, and means operated by said motor for periodically opening and closing said switch means, a selsyn transmitter drivingly connected to said motor, a selsyn motor mounted remotely from said transmitter at a point along said one highway, and speed indicating means operated by said selsyn motor whereby said speed indicating means is synchronized with the operation of said traffic control lights, said speed indicating means con prising endless belt, means for concealing portions of said belt, and speed indicia on said belt.

8. In a traff c control system for use at a highway intersec n, the combination, stop and go signal means, speed indicating light means arranged at the approaches to said intersection, first mean for periodically energizing said light means, and second for flashing of light means during the on point of said light means.

9. In a traffic control system for use at a highway intersection, the combination, stop and go signal means including a timing motor and switches operated thereby in a predetermined sequence for establishing stop and go periods, a selsyn transmitter drivingly connected to said motor, a selsyn motor, endless belt means driven by said selsyn motor, and speed indicating indicia on said endless belt, a portion of said endless belt having no speeds designated thereon.

10. In apparatus for scheduling the approach of motorists to an intersection of two or more highways so as to prevent motorists who approach the intersection on different highways from reaching the intersection at the same time, first means for regulating the speed of traffic on a first one of said highways, second means for regulating the speed on a second of said highways, and means for synchronizing the operation of said first and second named means whereby motorists traveling on said first and second named highways will not reach the highways simultaneously, said first and second named means comprising variable means for indicating recommended speed rates in terms of miles per hour for grouping the trafiic, said variable speed means operating cyclically so as to indicate the minimum speed for advance trafi'ic of a group and the maximum speed for the trailing trafiic of the same group.

11. In apparatus for scheduling the approach of motorists to an intersection of two or more highways so as to prevent motorists who approach the intersection on different highways from reaching the intersection at the same time, first means for regulating the speed of traffic on a first one of said highways, second means for regulating the speed on a second of said highways, and

or w) means for synchronizing th operation of said first and second named means whereby motorists traveling on said first and second named highways will not reach the highways simultaneously, said speed regulating means including means for indicating to the motorists in terms of miles per hour a minimum and a maximum permissible speed to be traveled while approaching the intersection, said last mentioned means grouping the traffic into platoons, the minimum speed being indicated to the advance traiilc of the platoon and the maximum speed being indicated to the trailing traffic of the platoon to thereby group the trafiic.

12. Means for regulating the speed of trafiic approaching an intersection of two or more highways, comprising in combination, a first speed indicating means visible to motorists traveling on a first of said highways for indicating to motorists on said first highway the speed to travel when approaching said intersection, a second speed indicating means visible to motorists traveling on a second of said highways for indicating to motorists on said second highway the speed to travel when approaching said intersection, each of said speed indi ating means indicating a minimum and a maximum speed cyclically so as to group the traflic into platoons, the minimum speed being indicated to the advance trafiic of a group and the maximum speed being indicated to the trailing traffic of the group so as to cause the trafiic to be bunched upon reaching the intersection and means for synchronizing the operation of said first and second speed indicating means whereby motorists traveling on intersecting highways will not be scheduled to reach the intersection simultaneously.

13. Means for regulating the speed of traffic approaching an intersection of two or more highways, comprising in combination, a first speed indicating means located along a first of said highways adjacent the approach to said intersection for indicating to motorists on said first highway the speed to travel, a second speed indicating means located along a second of said highways adjacent the approach to said intersection for indicating to motorists on said'second highway the speed to travel, and means for synchronizing and staggering the operation of said first and second speed indicating means whereby motorists traveling on intersecting highways will not be scheduled to reach the intersection simultaneously, each of said speed indicating means comprising means for cyclically and selectively indicating a plurality of appropriate speeds, the distance from the intersection to each of said speed indicating means divided by the indicated appropriate speed on one highway resulting in a time period alternating with the corresponding resulting time period on the other highway.

14. In a traffic control system, a speed indicator for use in regulating the speed of traffic over a given section of a h ghway comprising a housing, a plurality of numbers carried by said housing indicating different speeds to he traveled, light means associated with said numbers and supported by said housing, and means for selectively and cyclically energizing said light means so as to selectively designate different speeds to be traveled.

15. In a trafiic control system, a speed indicator for use in regulating the speed of traffic over a given section of a highway comprising a hous- 11 ing', a plurality of numbers indicating different speeds to be traveled, and means for selectively and cyclically displaying said numbers in a given sequence.

16. In a traffic regulating system for use in controlling the flow of tramc past an intersection comprising in combination, traffic control signal means at the intersection, variable speed indicating means for giving an indication which varies for each cycle of the traffic control means and is a function of the distance and the time available to reach the intersection when the signal at the intersection indicates go, said speed indicating means being spaced from said intersection along the highway approaching the intersection, and means for synchronizing the operation of said speed indicating means with the operation of said control signal means.

17. In an apparatus for controlling the flow of trafiic at an intersection of two or more highways, stop and go signal means of the type in which traffic is allowed to cross the intersection on only one highway at a time, varying speed indicating means mounted to be viewed by persons traveling over one of said highways including a plurality of numbers for selectively and cyclically indicating recommended speeds in terms of miles per hour, and means for operating said speed indicating means in synchronism with said stop and go signal means.

18. In apparatus for scheduling the approach of motorists to an intersection of two or more highways so as to prevent motorists who approach the intersection on different highways from reaching the intersection at the same time, first means for regulating the speed of traflic on a first one of said highways, second means for regulating the speed on a second of said highways, and means for synchronizing the operation of said first and second named means whereby motorists traveling on said first and second named highways will not reach the highways simultaneously, said first and second named means comprising variable means for indicating definite speed rates to be traveled in terms of miles per hour, said variable indicating means operating cyclically so as to group the traffic.

19. In apparatus for scheduling the approach of motorists to an intersection of two or more highways so as to prevent motorists who approach the intersection on different highways from reaching the intersection at the same time, first mean for regulating the speed of traflic on a first one of said highways, second means for regulating the speed on a second of said highways, and means for synchronizing the operation of said first and second named means whereby motorists traveling on said first and second named highways will not reach the highways simultaneously, said speed regulating means including variable means for indicating in terms of miles per hour to the motorists a minimum and a maximum permissible speed to be traveled while approaching the intersection, said variable means operating cyclically so as to indicate various recommended speeds for each cycle, which recommended speeds are a function of distance to the intersection and a function of time.

20. A traffic control system for use with a stop and go signal at an intersection, said system including auxiliary cue lights arranged at stations at predetermined intervals along the highway approaching the stop and go lights, the signals of each station including a plurality of indicia each setting forth a recommended rate of speed, the several indicia having speeds graduated from maximum to minimum recommended speed, control means for operating the stop and go signal at the intersection cyclically and alternately, said control means selecting the indicia in order from minimum to maximum speed at each station during each cycle of operation of the stop and go signal to thereby group the trafiic so that each group of traflic traveling at the recommended speed arrives at the intersection during the go signal period.

21. A traffic signal system, the combination including a stop and go signal operating alternately and cyclically, means for controlling the stop and go signals, and auxiliary cue signals along the highway at spaced intervals in the vicinity of the stop and go light, said cue signals being grouped at stations, the signals at each station including indicia having several recommended speeds, means for cyclically controlling the stop and go signals, said means including controls for cyclically controlling the cue signals such that the distance from the station to the stop and go signal divided by each recommended rate of speed equals the time falling within the time period that the go signal is energized.

References Cited in the file of this patent UNITED STATES PATENTS Niunber Name Date 1,042,316 Cantrall Oct. 22, 1912 1,824,572 Roberts Sept. 22, 1931 2,007,801 Halvorson July 9, 1935 2,082,479 Buerke June 1, 1937 2,241,998 Iwasaki May 13, 1941 2,407,432 Manewich Sept. 10, 1946 

